How to use PolyPaint and Spotlight Projection

Polypaint is a tool in brush that allows the creator to paint right on the model rather than painting on the UV map/layout in photoshop. It gives the creator more room to paint detail exactly where they want it to be. Using Polypaint and spotlight projections gives your model life. You don't just have to paint in polypaint, you can import an image into texture and using spotlight projection you can "paint" in the picture that you imported. This is useful for things such as realistic skin detail, eyeballs and things that are difficult to paint.

Turning on Polypaint

On your right menu, scroll down till you see "polypaint". Turn on colorize.

Once that is on. Turn on your RGB and turn off Zadd or Zsub

Also add the color menu to your side bar for convenience

You are now ready to use paint on your model. Size,brushes and opacity are the same tools you would use for sculpting.  ( In Alphas, draw size..etc)

But lets say you want to add paint on real skin texture.

Heres how:

Make sure your polypaint is turned on. Go into your "textures" menu and import a picture in. 

Put the image into the scene on top of you model. Z to turn on the options and turn on the "paint" button

Turn on Spotlight projection.

and you are ready to paint on the skin.  Paint like how you would normally but instead of just a solid color, Zbrush will project the image on to your model.

you can also press fillObject and it will fill the whole model with that image.

As you can see, the image is projected on to the model where i painted it in. Here's another example with an eyeball.

In conclusion, polypaint and spotlight projection is a great way to pay 2D textures to your models. It make make your model look more realistic and saves time. You can also export your polypaint to be used as a texture with your UV map.